There has been a long-standing desire to incorporate various components into detergent compositions, whose incorporation has not been feasible either because the particular components are not compatible with other particular components necessary in detergent compositions or because the detergent composition environment is generally hostile to the particular component sought to be incorporated. An example of the first type of problem is encountered when both an enzyme and a bleaching agent are put into a detergent composition. In such an instance, the bleaching agent tends to degrade the enzyme, thereby eliminating any cleaning benefit which the enzyme might afford. This is especially true where the detergent composition is a liquid, paste, foam, gel or other form in which the components are mobile. Thus, there has been work to develop bleach-free enzyme-containing detergent compositions.
An example of the second type of problem occurs when an enzyme is incorporated in a water-containing detergent composition designed for use in automatic dishwashers. Such detergent compositions are, by their nature, highly alkaline. The water in such compositions causes some of the alkaline components to ionize and these ions degrade the enzyme. Thus, after a relatively short period of storage, the detergent composition has lost the cleaning benefit which the enzyme affords.
Various approaches have been taken in order to permit the formulation of aqueous, alkaline detergent compositions containing enzymes. U.S. Pat. No. 3,472,783, Smillie, issued Oct. 14, 1969, recognized that the incorporation of an enzyme in an aqueous, alkaline detergent composition, will cause the enzyme to be denatured. As a result, the patent teaches substantially nonaqueous detergent compositions, not containing any alkaline builder salts, comprising a proteolytic enzyme and an ethoxylated nonionic surface active agent. A nonaqueous carrier, such as glycerine, may also be added to the compositions.
Another approach to permit the incorporation of enzymes in aqueous, alkaline detergent compositions has been to include enzyme-stabilizing agents in the compositions. Various stabilizing agents have been used. German Pat. No. 2,038,103, issued Feb. 10, 1972, to Henkel & Cie, discloses detergent compositions, containing enzymes, for use in automatic dishwashers, containing at least 40% water, and which include a sugar alcohol, a monosaccharide or a disaccharide which functions to stabilize the enzyme and prevent its degradation. U.S. Pat. No. 3,860,536, Landwerlen et al, issued Jan. 14, 1975, teaches enzyme-containing aqueous laundry detergent compositions which contain from 5 to 60% propylene glycol which stabilizes the enzymes in the aqueous detergent system. U.S. Published Patent Application B458,819, Weber, published Apr. 13, 1976, also discloses aqueous detergent compositions utilizing a stabilizing agent to prevent the degradation of the enzymes contained therein. The detergent compositions contain from 2 to 25% of specific detergency builder salts, from 5 to 30% of a specifically selected surface active agent, water, from 0.1 to 5% of a proteolytic enzyme, and from 5 to 40% of an enzyme stabilizing agent selected from alkali metal sulfates, alkali metal chlorides, glycerol and alkylene glycols having from 2 to 8 carbon atoms in the alkylene group.
It has now been found that by encapsulating a component, such as an enzyme, which would normally be unstable in a liquid water-containing detergent composition, in a material containing at least 10% by weight of a water-soluble normally solid alkoxylated nonionic surface active agent, preferably either polyethylene glycol having a molecular weight of from about 3000 to about 40,000 or the condensation product of tallow alcohol with from about 20 to about 80 moles of ethylene oxide, such components may be incorporated into such compositions, and will exhibit stability over periods of storage.
Accordingly, it is an object of this invention to permit the formulation of liquid water-containing detergent compositions which include beneficial components which would usually be unstable in such compositions.
It is a further object of this invention to permit the formulation of liquid water-containing detergent compositions which exhibit stability and effectiveness after periods of storage.
The above and other objects are now achieved by formulating the liquid detergent compositions as described below.